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Subject[PATCH 25/45] mm: add kernel_migrate_pages() helper, move compat syscall to mm/mempolicy.c
Date
Move compat_sys_migrate_pages() to mm/mempolicy.c and make it call a newly
introduced helper -- kernel_migrate_pages() -- instead of the syscall.

This patch is part of a series which tries to remove in-kernel calls to
syscalls. On this basis, the syscall entry path can be streamlined.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-mm@kvack.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
---
kernel/compat.c | 33 ---------------------------------
mm/mempolicy.c | 48 ++++++++++++++++++++++++++++++++++++++++++++----
2 files changed, 44 insertions(+), 37 deletions(-)

diff --git a/kernel/compat.c b/kernel/compat.c
index 3f5fa8902e7d..51bdf1808943 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -508,39 +508,6 @@ COMPAT_SYSCALL_DEFINE6(move_pages, pid_t, pid, compat_ulong_t, nr_pages,
}
return sys_move_pages(pid, nr_pages, pages, nodes, status, flags);
}
-
-COMPAT_SYSCALL_DEFINE4(migrate_pages, compat_pid_t, pid,
- compat_ulong_t, maxnode,
- const compat_ulong_t __user *, old_nodes,
- const compat_ulong_t __user *, new_nodes)
-{
- unsigned long __user *old = NULL;
- unsigned long __user *new = NULL;
- nodemask_t tmp_mask;
- unsigned long nr_bits;
- unsigned long size;
-
- nr_bits = min_t(unsigned long, maxnode - 1, MAX_NUMNODES);
- size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
- if (old_nodes) {
- if (compat_get_bitmap(nodes_addr(tmp_mask), old_nodes, nr_bits))
- return -EFAULT;
- old = compat_alloc_user_space(new_nodes ? size * 2 : size);
- if (new_nodes)
- new = old + size / sizeof(unsigned long);
- if (copy_to_user(old, nodes_addr(tmp_mask), size))
- return -EFAULT;
- }
- if (new_nodes) {
- if (compat_get_bitmap(nodes_addr(tmp_mask), new_nodes, nr_bits))
- return -EFAULT;
- if (new == NULL)
- new = compat_alloc_user_space(size);
- if (copy_to_user(new, nodes_addr(tmp_mask), size))
- return -EFAULT;
- }
- return sys_migrate_pages(pid, nr_bits + 1, old, new);
-}
#endif

/*
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index d879f1d8a44a..7399ede02b5f 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1377,9 +1377,9 @@ SYSCALL_DEFINE3(set_mempolicy, int, mode, const unsigned long __user *, nmask,
return do_set_mempolicy(mode, flags, &nodes);
}

-SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,
- const unsigned long __user *, old_nodes,
- const unsigned long __user *, new_nodes)
+static int kernel_migrate_pages(pid_t pid, unsigned long maxnode,
+ const unsigned long __user *old_nodes,
+ const unsigned long __user *new_nodes)
{
struct mm_struct *mm = NULL;
struct task_struct *task;
@@ -1469,6 +1469,13 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,

}

+SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,
+ const unsigned long __user *, old_nodes,
+ const unsigned long __user *, new_nodes)
+{
+ return kernel_migrate_pages(pid, maxnode, old_nodes, new_nodes);
+}
+

/* Retrieve NUMA policy */
SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
@@ -1571,7 +1578,40 @@ COMPAT_SYSCALL_DEFINE6(mbind, compat_ulong_t, start, compat_ulong_t, len,
return sys_mbind(start, len, mode, nm, nr_bits+1, flags);
}

-#endif
+COMPAT_SYSCALL_DEFINE4(migrate_pages, compat_pid_t, pid,
+ compat_ulong_t, maxnode,
+ const compat_ulong_t __user *, old_nodes,
+ const compat_ulong_t __user *, new_nodes)
+{
+ unsigned long __user *old = NULL;
+ unsigned long __user *new = NULL;
+ nodemask_t tmp_mask;
+ unsigned long nr_bits;
+ unsigned long size;
+
+ nr_bits = min_t(unsigned long, maxnode - 1, MAX_NUMNODES);
+ size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
+ if (old_nodes) {
+ if (compat_get_bitmap(nodes_addr(tmp_mask), old_nodes, nr_bits))
+ return -EFAULT;
+ old = compat_alloc_user_space(new_nodes ? size * 2 : size);
+ if (new_nodes)
+ new = old + size / sizeof(unsigned long);
+ if (copy_to_user(old, nodes_addr(tmp_mask), size))
+ return -EFAULT;
+ }
+ if (new_nodes) {
+ if (compat_get_bitmap(nodes_addr(tmp_mask), new_nodes, nr_bits))
+ return -EFAULT;
+ if (new == NULL)
+ new = compat_alloc_user_space(size);
+ if (copy_to_user(new, nodes_addr(tmp_mask), size))
+ return -EFAULT;
+ }
+ return kernel_migrate_pages(pid, nr_bits + 1, old, new);
+}
+
+#endif /* CONFIG_COMPAT */

struct mempolicy *__get_vma_policy(struct vm_area_struct *vma,
unsigned long addr)
--
2.16.2
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